Many medical devices, such as guide wires, intermittent and (cardio)vascular catheters or other medical tubing, syringes, and membranes require some sort of lubrication in order to facilitate insertion into or removal from the body. Pain or soft tissue damage can occur upon insertion or removal of the medical device if the medical device is not properly lubricated.
Many medical devices are coated with a hydrophilic coating that must be wetted with a liquid to attain the sufficient level of lubrication. A hydrophilic coating is typically provided as a coating on a surface of a medical device. The act of wetting a hydrophilic coating is performed by causing the hydrophilic coating to retain a wetting agent. Upon being wetted with a wetting agent, a hydrophilic coating may absorb at least two times its weight of the wetting agent and be rendered lubricious. A hydrophilic coating that does not absorb at least two times its weight of wetting agent will likely be insufficiently lubricous. The wetting agent may be any number of water or oil-based products, for example those disclosed in WO2006037321, assigned to Coloplast A/S, or WO2013017547, assigned to DSM IP Assets B.V.
Water-based wetting agents are often preferred by users. Unlike oil-based wetting agents, such as those that contain more than 50% by weight of propylene glycol or glycerol, water-based wetting agents do not have the disadvantage of leaving an oily residue on surfaces that come in contact with the wetted hydrophilic coating, such as a user's fingers. Furthermore, although a hydrophilic coating that is wetted with an oil-based wetting agent generally has good lubricious properties and dry-out time, improved lubricity can often be realized when a hydrophilic coating is wetted with a water-based wetting agent. Dry-out time is the amount of time that the wetted hydrophilic coating can retain suitable lubricious properties.
A hydrophilic coating may be wetted in a number of ways, depending on the composition of the wetting agent and the medical device design. For example, the hydrophilic coating may be wetted by submersing the hydrophilic coating in the wetting agent, spraying the wetting agent on the hydrophilic coating, running wetting agent over the hydrophilic coating for a short period of time, injecting the wetting agent into a packaging containing an article comprising a hydrophilic coating, or applying the wetting agent to the hydrophilic coating in the form of a gas, for instance in a high humidity environment.
The hydrophilic coating may be wetted immediately prior to use. Wetting immediately prior to use requires access to a wetting agent, for instance, a water source. Moreover, wetting immediately prior to use requires handling of the medical device at the risk of contacting the medical device with bacteria.
Because of the disadvantages with wetting the hydrophilic coating on a medical device immediately prior to use, numerous medical devices have been introduced that are sterile, pre-wetted, and individually packaged for immediate use. The use of so-called “ready-to-use” products may reduce the risk of contact with bacteria, and allows for the medical device to be used when access to a wetting agent is not practical or possible. A ready-to-use product typically comprises a wetted hydrophilic coating wherein the wetted hydrophilic coating comprises at least 70 wt %, or more preferably at least 90 wt % of wetting agent, based on the total weight of the wetted hydrophilic coating (i.e. the combined weight of the wetting agent and the hydrophilic coating). A product that does not possess a wetted hydrophilic coating that is sufficiently lubricious is not a ready-to-use product. An example of a ready-to-use product is described in U.S. Pat. No. 7,380,658, hereby incorporated by reference in its entirety.
In addition to numerous benefits, ready-to-use products present numerous challenges. One challenge faced is to avoid a reduction in the lubricious properties, durability, or dry-out time of the hydrophilic coating after sterilization. Certain sterilization techniques, such as sterilization with radiation, are known to potentially degrade the beneficial properties of a wetted hydrophilic coating. Consequently, various attempts have been made to reduce the damaging effects of sterilization on the beneficial properties of a hydrophilic coating wetted with a wetting agent comprising water prior to sterilization.
For example, a known technique described in WO/2000/030696, assigned to Coloplast A/S, involves wetting a hydrophilic coating on a medical device with an aqueous wetting agent comprising a hydrophilic polymer prior to sterilizing the medical device. However, the presence of polymers in the water phase can leave sticky residues on fingers and clothes. Moreover, an insufficiently cross-linked additional coating layer may be formed that is not acceptably durable. A similar technique disclosed in US2011/0106061, assigned to Coloplast A/S, suffers from similar disadvantages. This technique mentions a medical device comprising a hydrophilic coating, sterilized while in contact with a liquid comprising a hydrophilic polymer and a separate buffer selected from the group consisting of carboxylic acids, amino acids, aminosulphonic acids and inorganic acids.
Another known technique described in WO/2007/137699, assigned to DSM IP Assets B.V., involves the use of a compound selected from the group consisting of aliphatic compounds, alicyclic compounds and antioxidants for protecting a hydrophilic coating wetted with water. This technique may provide insufficient protection from the damaging effects of radiation at certain doses of radiation, such as greater than 30 kGy.
A further technique is disclosed in US2014/0271351, assigned to Coloplast A/S. This technique discloses a medical device comprising a hydrophilic coating, sterilized while in contact with a swelling medium comprising a low molecular polyol; and a separate buffer selected from the group consisting of carboxylic acids, amino acids, aminosulphonic acids and inorganic acids. The swelling media allegedly provides a stable pH after sterilization and maintains the low friction of the wetted hydrophilic coating.
An improved way of protecting a hydrophilic coating wetted with a wetting agent comprising water prior to sterilization from the damaging effects of radiation is desired.